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Classes in celestial navigation and related topics
 

Longitude by Lunars

"Lunar Distances" or lunars for short were used to determine longitude at sea in the period from about 1767 until 1850 (and rarely after that date). This was a time when chronometers were not yet widely available at a reasonable price and were considered unreliable on long voyages. The principle behind lunars is simple. The Moon in the sky is the hour hand of a great clock. The stars along its path are the numbers on the face of the clock. If we can measure the Moon's position relative to the stars, we can read the time from the clock. Comparing that absolute time with local time, usually determined by a time sight, we have our longitude. A one hour difference in time corresponds to a 15 degree difference in longitude.

Comments:


John Workman wrote:
I just took one of Franks classes and it was awesome!!

Frank taught an incredible class on celestial navigation that brought me from novice to some solid understanding of sextants, their history and most importantly their use as a aid to seeing the sea...and knowing where you are on this planet!

Hands on, wealth of knowledge, great resources ... he really covered a lot of ground! There was a lot of math but unlike in my youth, I was on the edge of my seat to soak up knowledge!! Frank made it relatable and real. The sextant which is such an iconic tool of the sea, was demystified. By the end of class i felt comfortable with it. I had mastered how it worked, how to read it and how to adjust it to insure its accuracy.

I came away with all of the cheat sheets and understandings of equations and concepts that breathe the life into what you capture through your sextant sightings.

I would highly recommend Frank and believe Mystic Seaport with its planetarium, an ideal setting for my class with him discovering this timeless tool of the sea.

Frank did a great job keeping the class interesting with visual aids, both on screen and out on the Seaport grounds.

All in all i would highly recommend this class to any and all folks interested in learning about navigation and sextants. Informative and digestible, but most of all useful to the point where i am comfortable with the instrument and have the formulas needed to continuing to set my sights on the horizon!!

I look forward to more classes to learn more from Frank and strengthen my understandings of celestial navigation!

Thank you!!!
John
John Brown wrote:
Frank
Thanks for a great app. The new option of using SI unit is really useful for us on the other side of the pond.
I have upgraded to the pro version and passed news of the upgrade to a friend learning to use her sextant. No doubt she will also relay this info.
Best regards
John Brown
Doug MacPherson wrote:
I recently took online versions of Frank Reed's "Celestial Navigation in the Age of Sail", and "Lunars - Finding Longitude by Lunar Distances". I couldn't have been more happy with them. Having originally learned post WWII celestial methods as an officer in the United States Navy, and taken it up as a hobby, I was quite familiar with that era's procedures. However, I was intrigued by how they managed prior to then. Frank's two classes filled that void. His vast knowledge of the subject, both the technical aspects of the work as well as the historical significance were perfectly balanced. These are classes that can be thoroughly enjoyed by both the novice as well as the well versed practitioner. Recipe's for doing the work, the science behind those recipes, and actual voyages by the sailors that practiced the art were all presented with wonderful clarity. If "time sights", "cleared lunar distances" or "apparent time" have ever roused an interest, you owe it to yourself to take one of Frank's classes.

Doug MacPherson
Lieutenant, USN sep.

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